1. Field of the Invention
The present invention relates to a very high throughput transmission, and more particularly, to a very high throughput transmission with contiguous and non-contiguous channels.
2. Description of the Related Art
Wireless local area network (WLAN) technology is widely established to provide access to the Internet with mobile devices. Conventionally, a typical WLAN communication system may use a transmission bandwidth of 20 MHz or 40 MHz. To achieve a higher throughput in WLAN communication systems, greater transmission bandwidths are desired. A WLAN communication system with 80 MHz bandwidth has, therefore, become a target. However, as WLAN technology becomes more popular and widely accepted, the spectrum occupied by WLAN communication systems is becoming more crowded. Accordingly, a contiguous 80 MHz bandwidth is not always available. As a result, non-contiguous transmission has been proposed to increase the probability of transmitting data with wider bandwidth. In a WLAN communication system with non-contiguous transmission bandwidth, the sub-channels of the WLAN communication system are not necessarily adjacent.
A phase rotation technique is introduced in the IEEE standard 802.11n that uses a bandwidth of 40 MHz to overcome the peak-to-average-power-ratio (PAPR) problem. However, such phase rotation technique cannot be directly applied to WLAN communication systems using 80 MHz or greater bandwidth, including those with non-contiguous channels. Therefore, there is a need for a signal phase rotation method that can reduce the PAPR for both contiguous and non-contiguous channel configurations.